Extended source
From Glossary of Meteorology
extended source
A producer of pollutants with an emission orifice generally more than about 10 m in size.
Examples include two-dimensional “area” sources such as agricultural and forest burning, volatile organic emissions from lagoons or other water treatment areas, and other open, expansive emission sources, or three-dimensional “volume” sources such as open buildings, tanks with several orifices, and other such structures.